Kakuro

Kakuro Instructions:
Here's how to play Kakuro:
Kakuro is a Japanese logic puzzle, hence the name.

The requirement is to fill all the empty cells in the grid with numbers (usually 1 - 9 are allowed) such that the sum total of the numbers in each run of empty cells matches the number given at the start of that run.

A number is not allowed to repeat within a run.

Kakuro, The Number Crossword

Kakuro puzzles are said to be the most popular logic puzzle in Japan - even more so than sudoku.

When sudoku launched in the UK and generally in the West and soon was seen everywhere, kakuro followed hot on its heels and was widely seen as being the surefire successor to the sudoku crown.

However to date no logic puzzle has superseded sudoku or seriously threatened its crown as the king of, and most ubiquitous of all, logic puzzles.

Kakuro never quite hit the same heights - and for many this is because it involves maths which is said to put some people off. Another explanation that has been given is that many of the kakuro generators on the market are of poor quality so either create trivial puzzles or ones that are so difficult they can only be solved by trial-and-error, which is no fun for a solver and leads ultimately to disillusionment with the puzzle type.

A good kakuro puzzle has one unique solution that can be reached without having to try insane numbers of combinations, but through some knowledge of the various combinations possible to make each sum, looking around the grid, solving bit by bit, and without ever having to resort to merely guessing at numbers and preparing for a lot of rubbing out.

Kakuro puzzles come at a range of different grid sizes and patterns, just like with crosswords.

It pays to learn the combinations that have few options, as with killer sudoku: for instance that a run of two cells with a total of '3' must be 2, 1 in some order and '4' must be 3, 1 since 2, 2 is not allowed as it has repetition.

There are number tables available online that list all the various combinations for a particular sum from a certain number of cells, and if tackling kakuro it is a good idea to familiarise oneself with these until you have done enough that they come as second nature. Certainly without these then kakuro puzzles can initially be something of a struggle!